I used to work in a place that was open 24/7/365. The keyboards were quite gross.
One lady used to bring rubbing alcohol and cotton swabs to clean the keys before she would touch them.
I sometimes would take a piece of paper, fold it so it was like a thin, pointed scoop, hold the keyboard on end, and run it down the rows between the keys.
Some of the stuff that would drop out was just...unidentifiable...fortunately. ? !
You might look into a can of compressed air to blow dust out from the keyboard...though a good vacuum is probably better.
